Some time ago last year, the creator of the game revealed on Twitter a button combination that can be used in-game on the main menu after loading a save to restore the original soundtrack on any version of the game. Source: https://twitter.com/PG_kamiya/status/1542368018604314624
The button combination he posted is for the Switch release, however I tested on PC and the equivalent inputs are:
With RT held, dpad-up dpad-down dpad-left dpad-right Y A X B (using an Xbox-prompt controller)
or
With CTRL held, W S A D middle-click space right-click left-click (using KBM)
Correctly completing the input plays a fanfare and can be reversed by simply repeating the process, and it seems as though the code has to be inputted each session as it doesn't appear to be saved.
Should this information be included on the Wiki page? As an in-game cheat it's not a fix, but it's a pretty relevant topic with fans of the game and it does technically make the SilentPatch method redundant (although the SilentPatch is better since it actually saves your music choice across sessions). Trying to use the SilentPatch method and the cheat at the same time doesn't seem to cause any harm: with the SilentPatch setting set to 0 the cheat functions as normal whereas when it's set to 1 it just forces the original music regardless of the cheat.